Continuing discussion on this: there are a nice series of different scale finding charts on the AAVSO web page (dated 1/2001, so preparation for the current outburst has been underway for quite some time!); for example, a CCD F-scale chart is http://charts.aavso.org/ccd/CAM/HTCAM-F.GIF Also, the Center for Backyard Astrophysics at http://cba.phys.columbia.edu/charts/ has a chart link to the Downes et al. 'Living Edition' chart at http://icarus.stsci.edu/~downes/cvcat/Images/cam_rxj0757.jpg My B&V field photometry file lists all stars in the field down to ~19th mag: http://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/htcam.dat and Bruce Sumner's extraction of a visual sequence is at http://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/sumner/htcam.seq If you are doing visual photometry, it is probably best to use the AAVSO charts since they have a standard sequence. If you are doing CCD photometry, any of the stars in Sumner's sequence, Skiff's sequence, the AAVSO CCD chart (based on Sumner), or the .dat file should work for comparison/check stars. In general, most of the interesting CVs have existing charts or standardization that can be found in the vicinity of the links given above, which should be your starting points. Arne